Analysis of samples absorbance susing UV-Vis

ANALYSIS OF SAMPLES ABSORBANCES USING ULTRAVIOLET-VISIBLE (UV-VIS) SPECTROSCOPY

BY:

I PUTU RAIWATA MERTANJAYA

(0813031019)

CHEMISTRY EDUCATION DEPARTMENT FACULTY OF MATHEMATICS AND SCIENCES GANESHA UNIVERSITY OF EDUCATION SINGARAJA 2011

ANALYSIS OF SAMPLES ABSORBANCES USING ULTRAVIOLET-VISIBLE (UV-VIS) SPECTROSCOPY

I.

Experiment Objective 1. Determine the copper content in the metal ore. 2. Determine the absorbance of Ethyl-p-methoxycinnamate (EPMS). 3. Determine the absorbance of natural indicator in acidic and basic solutions.

II. Theory Many modern technologies depend on the metal. Therefore, it has become imperative for a chemist to analyze metal ore to determine its content and develop a method for the determination of metals that have commercial value. One of the important metal in technological and economic value is copper. Copper is widely used for conductors, water pipes, and a mixture of various other metals, known as the alliance (such as brass, bronze, and silver coins). Spectrophotometry is widely used in laboratory analysis. Most laboratories that require identification and determination of organic compounds and inorganic compounds (eg pharmaceuticals, fertilizer, mining, etc.) using a spectrophotometer. In this trial will be determined percentage of the mass of copper in copper ore using spectroscopic techniques. Spectroscopy is the study of interaction of light (electromagnetic radiation) with matter (atoms and molecules). If certain wavelengths of light by an adsorbed atom or molecule, then the resulting absorption spectrum. Electronic structure of a species or a critical molecule absorption of light by species or molecule. The color complex compounds depends on the metal involved and the number of d orbitals has, associated with the oxidation state. However, there are several compounds of transition group has no d orbitals but the compounds are colored. The color is caused by electronic transitions involving the valence electrons in the other. Physicochemical analysis method based on spectral data is known as spectrometry. Several spectrophotometric methods is very important is ultraviolet (UV), infrared (IR), nuclear magnetic resonance (NMR), and mass. Ultraviolet and visible spectrophotometry can provide information about the chromophore group, which covalently unsaturated group contained in the molecule. The main components of spectrophotometer tool shown in the following scheme.

Beam Source

Monochromator

Sample

Detector

Screen Here are the types of UV-Vis:

(c) Double beam (DB)-in-time Absorption of light by molecules in the ultraviolet and visible spectral regions depend on the electronic structure of molecules. Absorption of this energy is quantized, namely the elevation of the orbital electrons in the ground state (ground state) to the orbital with higher energy (excited state = excited state), causing changes in the electronic energy of molecules,

namely the transition of valence electrons in the molecule. Various electronic energy levels or electronic transition can be summarized as follows:

Figure 1. Electronic Energy Levels Transition of n   * requires less energy than a transition    * or    * .  Transition of n   * (R band) of a single chromophore groups (such as carbonyl or nitro), the characteristic bands (  maks